Well, I'm an assistant librarian at a genealogy library, which is not exactly the same thing. I did my first shift this morning as a volunteer at the Midwest Historical and Genealogical Society in Wichita. We weren't busy this morning, so I split my time between administrative things like learning to use the copy machine and exploratory things like poking through the library catalog and the piles of data CDs next to the computer. The main librarian left us the task of checking a few of the obituary binders for missing pages and I was blown away by how much work the society has done on them, clipping obituaries, death notices and miscellaneous articles about accidents and murders from the Wichita Eagle and Beacon newspapers since 1955. The binders take up a whole bookcase.
It seems that local genealogy libraries have to split their focus to serve two different audiences -- those who live in the local area and want to research their lines, which requires resources about other areas, and those who are researching lines in the local area, but may not live there. The MHGS library reflects this -- the basement is devoted to Wichita and the surrounding areas, and includes resources the society has acquired, like city directories, and resources the society has created, like the obituary binders. The other two floors are more outward looking. Before joining the society, I had not appreciated how much material they have accumulated on other states; I had always assumed that, because my family arrived in Wichita in the 60's, local libraries wouldn't really have much to offer me. I stand corrected!